1D α-Fe₂O₃/ZnO Junction Arrays Modified by Bi as Photocathode: High Efficiency in Photoelectrochemical Reduction of CO₂ to HCOOH

Abstract

Photoelectrocatalytic (PEC) CO2 reduction to value-added chemicals is a promising solution to address the energy and environmental issues we face currently. Herein, a unique photocathode Bi@ZFO NTs (Bi and α-Fe2O3 co-modified ZnO nanorod arrays) with high utilization of visible light and sharp-tips effect are successfully prepared using a facile method. Impressively, the performance of Bi@ZFO NTs for PEC CO2 reduction to HCOOH included small onset potential (−0.53 V vs RHE), Tafel slope (101.2 mV dec–1), and a high faraday efficiency of 61.2% at −0.65 V vs RHE as well as favorable stability over 4 h in an aqueous system under visible light illumination. Also, a series of experiments were performed to investigate the origin of its high activity, indicating that the metallic Bi and α-Fe2O3/ZnO nanojunction should be responsible for the favorable CO2 adsorption/activation and charge transition/carrier separation, respectively. Density functional theory calculations reveal that the Bi@ZFO NTs could lower the intermediates’ energy barrier of HCOO* and HCOOH* to form HCOOH due to the strong interaction of Bi and α-Fe2O3/ZnO.

Simultaneous manipulation of scalable absorbance and the electronic bridge for efficient CO2 photoreduction

“…The stronger PL signal intensity represents the higher recombination rate of electron–hole pairs. 44,45 The peak intensity of bulk CN was stronger than that of CSCN-2, reflecting the inhibited recombination of photoexcited carriers after oxygen bridge modification, and is beneficial for photocatalytic CO 2 reduction (Fig. 8a).…”

A gradient Sn4+@Sn2+core@shell structure induced by a strong metal oxide–support interaction for enhanced CO2electroreduction

“…Accordingly, the more negative potential required for the production of CO might be due to the higher formation energy barrier of *COOH compared with that of *OCHO on Sn-based catalysts. 44 As the potential became more negative, the FE of CO displayed a volcano-like tendency. The peak values of 28.7% and 21.9% were observed at −0.76 and −0.86 V for SnO 2 /g-C 3 N 4 and SnO 2 /rGO, respectively.…”

Recent advancement in heterogeneous CO2 reduction processes in aqueous electrolyte

“…This photocathode was reported to be stable for 24 h operation under 1 sun illumination at −0.2 V RHE with 86.5% CO selectivity and a comparatively high photocurrent density of 5.1 mA cm −2 . In 2022, Ouyang et al 139 reported a 1D rough-surface α-Fe 2 O 3 /ZnO heterostructure nanorod array with Bi modification showing formate selectivity. The authors claimed that the sharp tip benefits from an accumulation of electrons on the active site, which enhances the catalyst activity.…”